HIV integrase (IN) is a viral enzyme required for integration of virus DNA into the host chromosome. This type of integration is highly specific for retroviruses, and HIV-1 IN is therefore a target for antiviral therapy. To design antivirals, it is essential to characterize IN. We have expressed the IN gene in E. coli as a fusion protein containing 23 amino acids of RT and all of IN. The cloned IN was reactive with both HIV-1 and HIV-2 positive sera. The recombinant protein was purified and used to immunize rabbits. The rabbit antisera are reactive with HIV-1 IN but not HIV-2 IN by Western blot, and also reactive with RT indicating that an antigenic epitope is present in the terminal 23 amino acids of RT. These data have recently been published in AIDS Research and Human Retroviruses (1990). In addition, 21 hybridomas have been prepared using the IN expressing clone and subcloned twice. 19 of these mAbs have specificity for IN and 2 for RT; all are IgG1, and all are reactive with HIV-1 but not HIV-2 by Western blot. An invention report has been filed and a manuscript is in preparation. An additional clone expressing only IN sequence has been constructed using PCR, as well as clones expressing the N- and C-terminal halves of IN. These clones have been examined for ability to bind DNA using a Southwestern blotting procedure. The complete IN molecule as well as the C-terminal protein bind DNA; the N-terminal portion exhibits no binding activity, suggesting that the C-terminal region contains the DNA binding site. A manuscript describing these findings is in preparation.